[Diy_efi] Ion Sensing project

[William Shurvinton]

I agree with Ville on this, in that that ION sensing is (in theory) ignition
agnostic. However, since you have to have a voltage generator at sround
400V, which just happens to be what CDI needs you can also use is to charge
a bank of capacitors for a CNP CDI system. By coupling the ignition and ION
sensing together you open up a number of interesting possibilities that can
keep the arc struck for a lot longer and get very good time control of when
the arc is extinguished.

So you can have 50Kv to bridge the spark gap, then 50A or so to ensure a
good fat flame kernel, hold it for 10°ish and turn it off just in time for
the ION sensing to start it's stuff. All nicely adjustable and possibly just
what the doctor ordered for engines where the pesky combustion chamber is
rotating whilst you are trying to light the mixture.

CDI through a dizzy I 'personally' rate along side catalytic converters,
chocolate tea pots and triumph herald suspension :-)

Bill
----- Original Message -----
From: Ville Vartiovaara <vvartiov at cc.hut.fi>
To: <diy_efi at diy-efi.org>
Sent: Thursday, July 04, 2002 3:18 PM
Subject: Re: [Diy_efi] Ion Sensing project


> > Seems like most of this is self defeating.
> > You want a long duration spark to get the reaction, as complete as
possible.
> > Sacrificng spark for detonation detection just doesn't seem like the
best
> > solution, to me.
> > The reason for CDIs is because you run out of dwell time for a proper
spark
> > with a auto transformer.   If you're not running a v8 at over 6K RPM
there
> > is no NEED for CDI.   You can do better ignition wise with DIS or CNP.
>
> As far as I remember, the CDI is being discussed here only to get some
> voltage level to compare to. :) Wheter it is CDI or not is not a problem
> as long as the spark is done until TDC.. Shouldn't be a problem. ;)
> And CDI has shorter decay time than a plain coil, so..



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